KOI-142 b
Astrophysical Synthesis & Habitability Characterization
KOI-142 b is a confirmed sub-neptune exoplanet orbiting the star KOI-142, located approximately 1229.2 light-years (376.86 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1235% across the stellar disk), this world measures 3.438 Earth radii (0.31 Jupiter radii) and has a measured mass of 9.5 Earth masses. Combining its mass and radius yields a mean bulk density of 1.29 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.8 g⊕ (7.85 m/s²), and an escape velocity of 18.6 km/s.
In its orbital architecture around KOI-142, KOI-142 b completes one full revolution every 10.916 Earth days at a semi-major axis of 0.09586 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 95.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.05561 carries the world between 0.0905 AU at periapsis and 0.1012 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 758 K (+485°C / +905°F) and receiving 68.56 S⊕ (~93,314 W/m²), KOI-142 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star KOI-142 is classified as a solar-type yellow star of spectral type G with an effective photospheric temperature of 5,466 K, a radius of 0.897 R☉, a mass of 0.99 M☉, an estimated bolometric luminosity of 0.644 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.6 Gyr and a metallicity of [Fe/H] = 0.27 dex (metal-rich relative to the Sun). From Earth, KOI-142 shines at apparent V-band magnitude 13.209 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The KOI-142 system is a multi-planet architecture hosting 3 confirmed worlds, with KOI-142 b sharing its stellar neighborhood alongside KOI-142 c, Kepler-88 d.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | KOI-142 |
| Spectral Type | G |
| Effective Temp (Teff) | 5,466 K |
| Stellar Radius | 0.8970 R☉ |
| Stellar Mass | 0.9900 M☉ |
| Bolometric Luminosity | 0.644 L☉ |
| Metallicity [Fe/H] | 0.270 dex |
| Stellar Age | 1.600 Gyr |
| Apparent Magnitude | V: 13.209 · G: 13.105 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.095860 AU |
| Orbital Period | 10.916 days |
| Mean Orbital Velocity | 95.5 km/s |
| Orbital Eccentricity (e) | 0.05561 |
| Orbital Inclination (i) | 90.9700° |
| Mean Bulk Density | 1.29 g/cm³ (18.6 km/s vesc) |
| Insolation Flux | 68.5630 S⊕ (~93,314 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1229.200 LY (376.863 pc) |